|Publication number||US6987432 B2|
|Application number||US 10/414,793|
|Publication date||17 Jan 2006|
|Filing date||16 Apr 2003|
|Priority date||16 Apr 2003|
|Also published as||CA2513976A1, CA2513976C, CA2805322A1, CA2805322C, CN1768475A, CN1768475B, EP1618658A2, EP1618658A4, EP1618658B1, US7071793, US7202761, US7362197, US20040207489, US20050162239, US20060186971, US20070188269, WO2004095696A2, WO2004095696A3|
|Publication number||10414793, 414793, US 6987432 B2, US 6987432B2, US-B2-6987432, US6987432 B2, US6987432B2|
|Inventors||Markus Lutz, Aaron Partridge|
|Original Assignee||Robert Bosch Gmbh|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (36), Non-Patent Citations (11), Referenced by (102), Classifications (28), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates generally to microelectromechanical systems (MEMS). MEMS are devices formed from miniaturized components operatively arranged on a substrate. These components are constructed through the use of lithographic and other micro-fabrication technologies to yield, for example, sensors and actuators.
Many common micromechanical structures are based on the reaction (e.g., oscillation, deflection or torsion) of a beam structure to an applied force. Such beam structures usually have, or are modeled to have, a rectangular cross section. However, the degree to which a beam is actually “rectangular” depends on the anisotropy of the etching method used to form it. Beams are used in the suspension of rigid plates, as lateral oscillators, or as cantilever devices. They are a natural choice for bearing-less motion detectors. Of particular note, MEMS increasingly use beams within resonator structures as part of clock and signal filtering circuits.
Single crystal semiconductors, such as silicon, are the obvious material of choice for the fabrication of resonator beams. Such materials have excellent mechanical strength and high intrinsic quality factor. Furthermore, the formation and processing of silicon-based materials are well-developed fields of endeavor drawing upon decades of experience from the integrated circuit industry.
Using polycrystalline silicon (“Poly Si”), for example, one may design resonators having great flexibility in geometry. However, the simple, but commonly used, bending beam and lateral oscillating beam structures will serve to illustrate not only some of the performance concerns associated with conventional resonators, but also the precepts of the present invention that follow.
When a force is applied to the surface of a beam, that surface is said to be stressed. The average value of this stress, σ, may be expressed as the loading force, F, divided by the area, A, over which it is applied, or:
When subjected to a stress, materials literally get pushed (or pulled) out of shape. Strain, ε, is a measure of this deformation, within the elastic limits of the material, and equals the change in length, ΔL, divided by the original length, LO, or:
Most materials of interest deform linearly with load. Since load is proportional to stress and deformation is proportional to strain, stress and strain are linearly related. The proportionality constant that relates these two measures is known as the elastic modulus or Young's modulus for the material and is given the symbol “E.” Young's moduli are known for a great range of materials.
The mechanical stiffness, kM, of a beam, as calculated with respect to the oscillation direction parallel to the width of the beam “w,” is proportional to its Young's modulus, E, and certain measures of its geometry, including for a beam with a rectangular cross section; length, “L,” and height, “h.”
As is well understood, the Young's modulus for most materials of interest changes with temperature according to known thermal coefficients (αE). For example, Poly Si has a thermal coefficient of 30 ppm/K°. Furthermore, the geometry of a beam structure also changes with temperature, generally expanding with increasing in temperature. Again, as an example, Poly Si has a thermal expansion coefficient, αexp, of 2.5 ppm/K°.
For some beam designs and related modeling purposes, and given a material with an isotropic thermal coefficient, the effect of thermal expansion on the width of the beam is essentially offset by the effect of thermal expansion on the length of the beam, thus resulting in a remaining linear effect on the height of the beam.
Setting aside electrostatic forces, the resonance frequency (f) of a beam may thus be defined under these assumptions by the equation:
where meff is the effective mass of the beam, constant over temperature.
Given the critical nature of a beam's resonance frequency to the overall performance of the resonator, it must remain relatively stable over a range of operating temperatures. In view of the relationship set forth in EQUATION 2, frequency will remain constant only if the mechanical stiffness remains constant. This, however, will not normally be the case as thermally induced changes to the Young's modulus tend to change in the mechanical stiffness of the beam. Accordingly, some external influence is required to “compensate” for the inevitable changes in resonance frequency due to variations in temperature.
Prior attempts have been made to address the issue of resonant beam frequency stabilization in the presence of changing temperature. See, for example, Wan-Thai Hsu, Stiffness-Compensated Temperature Insensitive Micromechanical Resonators, MEMS 2002 (-7803-7185-2/02 IEEE). Such attempts have, however, focused on the issue of vertical oscillation compensation and have prescribing the remedial use of gold or similar materials that are incompatible with CMOS integration.
For other beam designs and related modeling purposes, the frequency (f) of a resonance beam having a rectangular cross section may be expressed by the following equation:
where “ρ” is the density of the material forming the beam, and “S” is an elastic strain applied to the beam.
As temperature rises, both L and t increase due to thermal expansion, but the effect of the changes in L dominate due to the fact that L is much, much greater than t. As a result, the frequency tends to decrease as temperature increases, and vice versa. Also apparent from the foregoing equation, compressive strain applied to the beam with increasing temperature will enhance frequency sensitivity as a function of temperature. Conversely, tensile strain applied to the beam with increasing temperature will retard frequency sensitivity as a function of temperature. Such conditions can be better understood by first assuming a desired relationship wherein the change in frequency, d(f) as a function of the change in temperature, d(T) is equal to 0. Substituting and equating expressions yields:
For most practical situations, the applied strain, S, will be much, much less than one. Under such assumptions, the relationship described in EQUATION 4 becomes:
It is again apparent from this relationship that thermally induced changes to the resonant frequency of a beam may be retarded (i.e., compensated for) or enhanced by changes in an elastic strain, (d(S)), applied to the beam.
Unfortunately, the thermal coefficient of Young's modulus for silicon is in the order of 30 ppm/K. This reality leads to considerable temperature drift in the frequency of an oscillating beam in the range of 18 ppm/C°. Given nominal requirements for temperature stabilities ranging from 0.1 to 50 ppm, and common operating temperature specifications ranging from −40 C° to +85 C°, the putative MEMS designer faces a considerable challenge in the design of a temperature stable resonator.
Clearly, an efficient compensation mechanism is required for frequency stability of micromechanical resonators over an operating temperature range. Such a mechanism should not rely on the incorporation of materials incompatible with CMOS integrations.
The present invention addresses the issues of temperature compensation for micromechanical resonators. Both active and passive solutions are presented. Indeed, employing both active and passive techniques in the same solution is also presented. Active solutions are characterized by the application of an external influence on the resonator from a circuit or mechanism external to the resonator structure itself. Passive solutions draw upon the inherent and disparate thermal expansion qualities found in the semiconductor materials selected to form the resonator structure.
In a first aspect, the present invention provides an active method of compensating for thermally induced frequency variations in a micromechanical resonator including an oscillating beam and an electrode. The method includes determining the actual operating frequency for the beam in relation to a desired resonance frequency, and thereafter applying a compensating stiffness to the resonator to maintain the desired resonance frequency. In one related embodiment, the compensating stiffness is provided by an electrostatic force applied to the beam by the electrode.
Within certain active, compensation solutions, the frequency for a resonator may be determined using a feedback circuit that either directly detects actual operating frequency, or that detects the operating temperature of the resonator. In response to a corresponding output signal from the feedback circuit, a voltage applied to the electrode may be varied to provide a compensating, electrostatic stiffness on the oscillating beam.
In an alternative set of active, compensation solutions, a working gap between the oscillating beam and the electrode is adjusted to vary the compensating stiffness applied to the beam.
However, other aspects of the present invention are readily applicable to passive approaches to frequency stabilization of a resonator over an operating temperature range. For example, one method of fabricating a micromechanical resonator according to the present invention forms a beam structure and/or related support structure(s) from a first material, and the electrode, at least in part, from a second material. Where the first and second materials are properly selected with disparate thermal expansion coefficients, the relative expansion of these components with temperature will tend to passively adjust the working gap between the beam and electrode to vary a compensating stiffness applied to the beam, such that resonator frequency remains substantially stable over a prescribed temperature range.
There are myriad ways to form an electrode having an effective thermal expansion coefficient that differs from the substrate, the beam, and/or the support structures for the beam. Lever arms may be used to magnify the effects of disparate thermal expansion. In one related embodiment, an electrode and beam are formed from an active layer deposited on a semiconductor substrate. The active layer has a first thermal expansion coefficient. Thereafter, the body of the electrode is modified to incorporate a second material having a different thermal expansion coefficient. Within this and similar embodiments, the first and/or second materials may be conveniently selected from a group of possible materials including; silicon, poly-silicon, Epi-Poly, LPCVD-Poly, silicon dioxide, germanium, silicon-germanium compounds, silicon nitrides, and silicon carbide.
In yet another set of passive compensation solutions, a micromechanical resonator is formed on a substrate of first material type. An oscillating beam, related support structure(s), and/or an electrode are thereafter formed from an active layer of second material type. Anchors for the support structure(s) and the electrode may be placed at different lateral positions on the substrate, such that relative thermal expansion of these components on the substrate will tend to adjust a working gap between the beam and the electrode to thereby compensate for frequency variations in the beam's oscillations over temperature.
In another closely related aspect, the present invention provides a micromechanical resonator, suspended over a substrate by means of an anchor. At one point, the anchor fixes the beam to the substrate, but the anchor also includes a composite structure formed from two or more materials having different thermal expansion coefficients. Where the materials used to form the anchor are properly selected in relation to the material used to form the substrate, relative thermal expansion between these materials may be used to apply a compressive or tensile strain on the beam. An appropriate strain upon the beam tends to compensate for thermally induced frequency variations. Lever arms may be incorporated into a resonator design to amplify the compressive or tensile strain applied to the beam.
In the course of the detailed description to follow, reference will be made to the attached drawings. These drawings show different aspects of the present invention and, where appropriate, reference numerals illustrating like structures, components, materials and/or elements in different figures are labeled similarly. It is understood that various combinations of the structures, components, materials and/or elements, other than those specifically shown, are contemplated and are within the scope of the present invention.
FIGS. 8 and 9A-C illustrate the use of laterally disposed and composite anchors within yet other aspects of the present invention;
The description that follows presents several design possibilities, methods, and/or mechanical structures in surface micromachining, whereby thermally induced frequency changes in a micromechanical resonator may be remedied. According to the present invention, semiconductor compatible materials are highly preferred in the fabrication of such resonators.
Throughout the description that follows, semiconductor compatible materials are presumed in the teaching examples. This materials bias is understandable given the contemporary emphasis in CMOS integration of micromechanical structures. However, materials incompatible with such designs may also be used, albeit with fewer current design advantages. Compatible materials are not limited to silicon or silicon-based compositions, but include all materials capable of being fabricated by conventional integrated circuit techniques and/or integrated upon a semiconductor substrate. As presently preferred, resonators according to the present invention may be discrete or readily integrated into larger MEMS devices and/or devices including integrated circuits (for example, CMOS circuitry).
In effect, the present invention eliminates the temperature coefficient of the Young's modulus for the material(s) from which a resonator is formed. The term “resonator” encompasses all structures having, or capable of having, a desired mechanical or electro-mechanical vibration. In the examples that follow, resonators are formed from beam structures having presumptively rectangular cross sections. This assumption derives from the obvious fact that explanations drawn to a resonant beam having a rectangular cross sections are more easily understood than non-rectangular beam structures. The present invention is not, however, limited to resonant beams having rectangular cross sections.
As discussed above, the frequency of a resonator is known to vary (or drift) in relation to temperature. Thus, some compensation mechanism is required to hold the resonator “on frequency” under the influence of a variable operating temperature. Thermal compensation is preferably provided by means of design geometry, rather than process parameters. Furthermore, passive (or inherent) thermal compensation is preferred over active control accomplished by an external circuit. Yet, the present invention is also applicable to active thermal compensation solutions.
Several presently preferred embodiments of the invention are described below. These embodiments are examples teaching the use and making of the invention. They are, however, only examples and do not fully circumscribe the bounds of the present invention which is defined by the claims that follow.
Recall from EQUATION 2 above that the frequency of a resonator, absent the effect of electrostatic forces, may be defined in relation to its mechanical stiffness, kM. In order to maintain a constant frequency, independent of temperature, it is necessary to compensate for the inevitable variations in the frequency of the resonator.
In one aspect of the present invention, a compensating stiffness is applied to the resonator to counteract thermally induced frequency changes. The term “compensating stiffness” broadly denotes any remedial force applied to the resonator. Unlike mechanical stiffness, which derives from the internal composition of the resonator, compensating stiffness results from an external force applied to the physical form of the resonator.
For example, an electrostatic force may be used as a compensating stiffness in the resonator. The electrostatic force, Fel, between an electrode and an oscillating beam may be expressed as:
where ∈ is the dielectric constant, A is the area between the beam and electrode, d is the gap between the beam and the electrode, x is the deflection due to oscillation, and U is the applied voltage.
Where the deflection due to oscillation is negligible, the compensating electrostatic stiffness may be expressed as:
Expressed in terms of EQUATION 2 above, the frequency of a resonator as defined by its mechanical stiffness and an externally applied electrostatic stiffness may be expressed as:
Looking at EQUATIONS 7 and 8, it is apparent that temperature induced variations in the mechanical stiffness, and thus the resonance frequency, may be offset or compensated for by an equal variation in the electrostatic stiffness. Given fixed values for the dielectric constant and the field area, changes in the compensating electrostatic stiffness may be effected by changing the applied voltage U or by changing in the working gap between the beam and the electrode.
Thus, broadly characterized within an active compensation method, one aspect of the present invention may be summarized as (1) determining an actual operating frequency for the resonator, and (2) applying, as needed, a compensating stiffness to the beam, such that a desired resonance frequency is maintained over an operating temperature range. The step of determining the actual operating temperature may be accomplished by any one of a number of conventional feedback circuits directly measuring resonator frequency, or indirectly determining the operating frequency in relation to another measured parameter, such as temperature. In many instances, such data may already exist within the contemplated use of the resonator and may be advantageously used for the purpose of resonator temperature compensation.
This concept can be better understood by considering the example illustrated in
It should be noted that the term “height” is an arbitrary designation in relation to the rectangular example illustrated by the top view shown in
The support structures 7 and 8, electrode 2, and resonator 1 are preferably all formed from CMOS compatible, silicon-based material. These components may be formed from an active layer deposited on a semiconductor substrate, or from separately deposited layers. The term “deposited” merely describes the placement of an active layer on the substrate. It is not process or fabrication technique specific.
Support structures 7 and 8, electrode 2, and beam 1 will expand (and contract) in accordance with the thermal expansion coefficient for their material(s) of their composition. For example, support structures 7 and 8 are assumed to expand away from the point at which they are fixed to the substrate, i.e., in the direction of vector 10 shown in FIG. 2A. Electrode 2 is assumed to expand in the direction of vector 11. While thermal expansion vectors 10 and 11 are shown to be directionally coincident in the example of
Within the context of the working example, the following parameters may be manipulated during design to achieve temperature compensation during operation of the resonator: (a) the ratio between support structure height L1 and electrode height L2; (b) the ratio between a (first) thermal expansion coefficient for material used to implement the support structures 7 and 8, and a (second) thermal expansion coefficient for material used to implement the electrode 2; and, (c) the distance across the working gap. Additionally, the applied voltage U may be varied in relation to temperature during resonator operation to compensate for temperature induced changes in frequency. Naturally, different resonator geometries will yield different parameters and inter-component relationships that may be manipulated to effect thermal frequency compensation.
In addition to the active compensation solutions discussed, parameters (a) through (c) above may be passively adjusted during operation by, for example, a careful selection of disparate composition materials used to respectively implement the support structures and the electrode. The term “passive” (or passively) as used here refers to a process, method, or adaptation wherein one or more parameters are changed under the influence of changes (e.g., thermal expansion) to one or more components internal to the design. Passive adjustments are distinct from “active” adjustments that require the application of an externally derived force or influence.
Returning to the relationship between frequency, mechanical stiffness, kM, and the compensating electrostatic stiffness kel described in EQUATION 8, it is clear that any increase in kM must be matched by an equivalent (or nearly equivalent) increase in kel in order for frequency f to remain stable. As noted in EQUATION 1, the mechanical stiffness, kM, for a resonator formed from a silicon based material will increase in relation to an increase in its Young's modulus, E. In order to offset this increase in kM, and an increased kel must be derived.
Looking again at EQUATION 7 and assuming a fixed dielectric constant, ∈, and field area, A, kel may be increased by increasing the applied voltage, U, and/or by reducing the working gap, d, between the resonator and the electrode. Increasing applied voltage U is a simple, active solution. A conventional feedback circuit (shown in block diagram form in
Active temperature compensation is attractive in its ability to adapt real-time to temperature variations. However, active compensation schemes come at the price of some significant additional overhead in the form of actuation drivers and/or extension mechanisms. Thus, in many applications a passive temperature compensation solution is desirable.
In similar vein, the example illustrated in
In the example shown in
In the related example shown in
The foregoing examples have described electrode structures formed from at least one additional (secondary) material having a thermal expansion coefficient different from the thermal expansion coefficient of a (first) primary material forming the other associated components in a resonator structure. However, the present invention also contemplates similar alteration of the support structures, the anchors, and/or the beam in similar manner. It is not necessary that any one of these components be formed from a combination of materials, refilled or otherwise combined. Rather, materials having disparate thermal expansion coefficients may be used to form respective components in a resonator. For example, the beam, support structures, and anchors could be formed from EpiPoly and the electrode from germanium.
Additionally, the direction and magnitude of relative component expansion to effect working gap adjustment may be amplified by the use of one or more lever arms.
Relative anchor locations on a substrate may also be used to adjust a separation gap between an electrode and beam. This result may be achieved by considering during the design process the different thermal expansion coefficients between the substrate and one or more active layer(s) deposited on the substrate. This approach is illustrated in FIG. 8.
Here, an electrode 29 is separated from beam 1 across a working gap. Electrode 29 is fixed to the substrate at anchor 29A. In contrast, supports 7 and 8 fix beam 1 to the substrate at respective anchors 7A and 8A. Assuming, as examples, that the substrate is silicon of sapphire (SOS) and the active layer is EpiPoly, the lateral distance L3 between the respective anchors, as measured in the direction of thermal expansion for the beam, will adjust the working gap over a range of operating temperatures.
Relative anchor composition may also be used to effect thermal compensation for resonance beam frequency variations. Recognizing that compressive strain tends to decrease the resonant frequency of a beam and tensile strain tends to increase the resonant frequency, anchors having a thermal expansion coefficient different from the substrate may be used to induce a compressive or tensile strain on the beam. This approach is illustrated in
Here, a bending (or suspended) beam 1 is supported over substrate 3 by anchors 50 and 52. By forming anchors from two or more materials having in combination a different thermal expansion coefficient from that of the substrate, a compressive or tensile strain may be exerted on beam 1. As above, substrate 3 may be formed from many conventional materials including, without limitation, silicon and germanium.
Anchors 50 and 52 are respectively fixed to substrate 3 at anchor points 50A and 52A. The composite anchors may be formed, for example, by SiO2 re-fill into selectively vacated portions of an EpiPoly anchor body. This would result in composite anchors 50 and 52 having a lower overall thermal expansion coefficient with respect to an EpiPoly beam and/or a silicon-based substrate. The length of the composite anchors, L4, as measured between an anchor point and the beam, provides leverage for the compressive or tensile strain applied to beam 1 by the disparate thermal expansion of the selected materials.
The relative beam composition may also be used to effect thermal compensation for resonance beam frequency variations. In this regard, with reference to
The invention illustrated in
Composite anchors 61 and 62 are combined in
Throughout the foregoing disclosure, selected bending beam or lateral oscillating beam structures have been used as examples. However, the frequency compensation schemes thus illustrated are not limited to the exemplary structures, but have application to all beams useful in MEMs. Further, various materials have been suggested for composition of the exemplary components. Again, these are merely presently preferred examples. So, long as resonator components are properly designed and fabricated with materials having sufficiently disparate thermal expansion coefficients, the passive and/or active frequency compensation solutions taught herein may be achieved.
Moreover, the passive techniques and active techniques described and illustrated herein may also be combined or integrated to provide a solution that employs both passive and active compensation techniques. For example, the embodiments of FIG. 3 and FIGS. 4A and/or 4B may be integrated to provide both a passive and active approach (see, for example, FIG. 11).
Throughout this application the term “compensation” and “compensate” (or similar terms) are used to denote a remedial process by which a major component or factor of the conditions adversely influencing resonator stability is addressed and/or ameliorated. Other issues, and even issues relating to thermal expansion, such as changes in geometries (for example, height and/or width) may be less significant in the overall impact on the compensation. Moreover, the approach herein may be well suited to address, compensate for, and/or ameliorate conditions adversely influencing resonator stability over a finite range of temperature variations (for example, a predetermined temperature range).
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US5640133 *||23 Jun 1995||17 Jun 1997||Cornell Research Foundation, Inc.||Capacitance based tunable micromechanical resonators|
|US6199874 *||7 Dec 1995||13 Mar 2001||Cornell Research Foundation Inc.||Microelectromechanical accelerometer for automotive applications|
|US6278337 *||5 Oct 1999||21 Aug 2001||Stmicroelectronics, Inc.||Integrated released beam oscillator and associated methods|
|US6324910||15 Oct 1997||4 Dec 2001||Robert Bosch Gmbh||Method and device for measuring a physical variable|
|US6355534||26 Jan 2000||12 Mar 2002||Intel Corporation||Variable tunable range MEMS capacitor|
|US6445106||18 Feb 2000||3 Sep 2002||Intel Corporation||Micro-electromechanical structure resonator, method of making, and method of using|
|US6479921||9 Jan 2002||12 Nov 2002||Intel Corporation||Micro-electromechanical structure resonator, method of making, and method of using|
|US6504641 *||1 Dec 2000||7 Jan 2003||Agere Systems Inc.||Driver and method of operating a micro-electromechanical system device|
|US6529093||6 Jul 2001||4 Mar 2003||Intel Corporation||Microelectromechanical (MEMS) switch using stepped actuation electrodes|
|US6531668||30 Aug 2001||11 Mar 2003||Intel Corporation||High-speed MEMS switch with high-resonance-frequency beam|
|US6570468||29 Jun 2001||27 May 2003||Intel Corporation||Resonator frequency correction by modifying support structures|
|US6573822||18 Jun 2001||3 Jun 2003||Intel Corporation||Tunable inductor using microelectromechanical switches|
|US6586836||1 Mar 2000||1 Jul 2003||Intel Corporation||Process for forming microelectronic packages and intermediate structures formed therewith|
|US6593672||22 Dec 2000||15 Jul 2003||Intel Corporation||MEMS-switched stepped variable capacitor and method of making same|
|US6600389||30 May 2001||29 Jul 2003||Intel Corporation||Tapered structures for generating a set of resonators with systematic resonant frequencies|
|US6604425 *||9 Jun 2000||12 Aug 2003||Hrl Laboratories, Llc||Microelectromechanical correlation device and method|
|US6635940 *||23 Apr 2002||21 Oct 2003||Hewlett-Packard Development Company, L.P.||Micro-electromechanical actuator and methods of use|
|US6713938 *||20 Apr 2001||30 Mar 2004||The Regents Of The University Of Michigan||Method and apparatus for filtering signals utilizing a vibrating micromechanical resonator|
|US20020074621||5 Nov 2001||20 Jun 2002||Peng Cheng||Variable tunable range mems capacitor|
|US20020074897||15 Dec 2000||20 Jun 2002||Qing Ma||Micro-electromechanical structure resonator frequency adjustment using radient energy trimming and laser/focused ion beam assisted deposition|
|US20020096967||9 Jan 2002||25 Jul 2002||Qing Ma||Micro-electromechanical structure resonator, method of making, and method of using|
|US20020180563||30 May 2001||5 Dec 2002||Qing Ma||Tapered structures for generating a set of resonators with systematic resonant frequencies|
|US20020190603||11 Jun 2001||19 Dec 2002||Qing Ma||Apparatus for adjusting the resonance frequency of a microelectromechanical (MEMS) resonator using tensile/compressive strain and applications therefor|
|US20030001694||29 Jun 2001||2 Jan 2003||Qing Ma||Resonator frequency correction by modifying support structures|
|US20030006468||27 Jun 2001||9 Jan 2003||Qing Ma||Sacrificial layer technique to make gaps in mems applications|
|US20030006858||6 Jul 2001||9 Jan 2003||Qing Ma||Microelectromechanical (mems) switch using stepped actuation electrodes|
|US20030042117||30 Aug 2001||6 Mar 2003||Intel Corporation||High-speed mems switch with high-resonance-frequency beam|
|US20030048520||7 Sep 2001||13 Mar 2003||Intel Corporation||Vacuum-cavity MEMS resonator|
|US20030051550||13 Aug 2002||20 Mar 2003||Nguyen Clark T.-C.||Mechanical resonator device having phenomena-dependent electrical stiffness|
|US20030062961||28 Sep 2001||3 Apr 2003||Qing Ma||Center-mass-reduced microbridge structures for ultra-high frequency MEM resonator|
|US20030077871||17 Sep 2002||24 Apr 2003||Intel Corporation||Fabrication of on-package and on-chip structure using build-up layer process|
|US20030085109||2 Nov 2001||8 May 2003||Intel Corporation||MEMS switch having hexsil beam and method of integrating MEMS switch with a chip|
|US20030085779||27 Nov 2002||8 May 2003||Qing Ma||Resonator frequency correction by modifying support structures|
|US20030112097||28 Mar 2002||19 Jun 2003||Intel Corporation||Film bulk acoustic resonator structure and method of making|
|US20030132824||15 Jan 2003||17 Jul 2003||Intel Corporation||High-speed MEMS switch with high-resonance-frequency beam|
|US20030160539||27 Feb 2003||28 Aug 2003||Qing Ma||Apparatus for adjusting the resonance frequency of a microelectromechanical (MEMS) resonator using tensile/compressive strain and applications thereof|
|1||"Active Frequency Tuning for Micro Resonators by Localized Thermal Stressing Effects", Remtema et al., Elsevier, Sensors and Actuators A 91 (2001), pp. 326-332.|
|2||"Crystal Oscillator Design and Temperature Compensation", Marvin E. Frerking, Litton Educational Publishing, Published by Van Nostrand Reinhold Company, 1978, ISBN 0-442-22459-1, Chapter 10, pp. 130-176.|
|3||"Fine Frequency Tuning in Resonant Sensors", Cabuz et al., IEEE, 1994, pp. 245-250.|
|4||"Frequency Trimming and Q-Factor Enhancement of Micromechanical Resonators Via Localized Filament Annealing", Wang et al., IEEE Transducers '97, 1997 International Conference on Solid-State Sensors and Actuators, Chicago, Jun. 16-19, 1997, pp. 109-112.|
|5||"Geometric Stress Compensation for Enhanced Thermal Stability In Micromechanical Resonators", Hsu et al., IEEE Ultrasonics Symposium, 1998, pp. 945-848.|
|6||*||"Independent Tuning Of The Linear And Nonlinear Stiffness Coefficients Of A Micromechanical Device", Adams et a., IEEE Jun. 1996, pp. 32-37.|
|7||"Mechanically Temperature-Compensated Flexural-Mode Micromechanical Resonators", Hsu et al., IEEE IEDM, 2000, pp. 399-402.|
|8||"MEMS Resonators That Are Robust to Process-Induced Feature Width Variations", Liu et al., IEEE International Frequency Control Symposium and PDA Exhibition, 2001, pp. 556-563.|
|9||"MEMS Resonators That Are Robust to Process-Induced Feature Width Variations", Liu et al., IEEE Journal of Microelectromechanical Systems, vol. 11, No. 3, Oct. 2002, pp. 505-511.|
|10||"Stiffness-Compensated Temperature-Insensitive Micromechanical Resonators", Hsu and Nguyen, IEEE, Feb. 2002, pp. 731-734.|
|11||*||"VHF Fre-Free Beam High-Q Micromechanical Resonators", Nguyen et al., IEEE 1999, pp. 453-458.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7161730 *||22 Jul 2005||9 Jan 2007||Idc, Llc||System and method for providing thermal compensation for an interferometric modulator display|
|US7591201||9 Mar 2007||22 Sep 2009||Silicon Clocks, Inc.||MEMS structure having a compensated resonating member|
|US7625825||14 Jun 2007||1 Dec 2009||Qualcomm Mems Technologies, Inc.||Method of patterning mechanical layer for MEMS structures|
|US7639104 *||9 Mar 2007||29 Dec 2009||Silicon Clocks, Inc.||Method for temperature compensation in MEMS resonators with isolated regions of distinct material|
|US7660031||7 Feb 2008||9 Feb 2010||Qualcomm Mems Technologies, Inc.||Device and method for modifying actuation voltage thresholds of a deformable membrane in an interferometric modulator|
|US7679812||21 Jul 2006||16 Mar 2010||Qualcomm Mems Technologies Inc.||Support structure for MEMS device and methods therefor|
|US7704773||18 Aug 2006||27 Apr 2010||Qualcomm Mems Technologies, Inc.||MEMS devices having support structures with substantially vertical sidewalls and methods for fabricating the same|
|US7706042||20 Dec 2006||27 Apr 2010||Qualcomm Mems Technologies, Inc.||MEMS device and interconnects for same|
|US7709964||26 Oct 2007||4 May 2010||Qualcomm, Inc.||Structure of a micro electro mechanical system and the manufacturing method thereof|
|US7711239||19 Apr 2006||4 May 2010||Qualcomm Mems Technologies, Inc.||Microelectromechanical device and method utilizing nanoparticles|
|US7719752||27 Sep 2007||18 May 2010||Qualcomm Mems Technologies, Inc.||MEMS structures, methods of fabricating MEMS components on separate substrates and assembly of same|
|US7747109||18 Aug 2006||29 Jun 2010||Qualcomm Mems Technologies, Inc.||MEMS device having support structures configured to minimize stress-related deformation and methods for fabricating same|
|US7806586||2 Jun 2006||5 Oct 2010||The Board Of Trustees Of The Leland Stanford Junior University||Composite mechanical transducers and approaches therefor|
|US7824098||21 Jan 2008||2 Nov 2010||The Board Of Trustees Of The Leland Stanford Junior University||Composite mechanical transducers and approaches therefor|
|US7863079||5 Feb 2008||4 Jan 2011||Qualcomm Mems Technologies, Inc.||Methods of reducing CD loss in a microelectromechanical device|
|US7875485||27 Jul 2009||25 Jan 2011||Qualcomm Mems Technologies, Inc.||Methods of fabricating MEMS devices having overlying support structures|
|US7936031||21 Jul 2006||3 May 2011||Qualcomm Mems Technologies, Inc.||MEMS devices having support structures|
|US7944124 *||29 Aug 2008||17 May 2011||Silicon Laboratories Inc.||MEMS structure having a stress-inducer temperature-compensated resonator member|
|US7956517||4 Sep 2008||7 Jun 2011||Silicon Laboratories||MEMS structure having a stress inverter temperature-compensated resonator member|
|US7990229||19 Jun 2008||2 Aug 2011||Sand9, Inc.||Methods and devices for compensating a signal using resonators|
|US7999635||29 Jul 2008||16 Aug 2011||Silicon Laboratories Inc.||Out-of plane MEMS resonator with static out-of-plane deflection|
|US8044736||29 Apr 2008||25 Oct 2011||Sand9, Inc.||Timing oscillators and related methods|
|US8044737||29 Apr 2008||25 Oct 2011||Sand9, Inc.||Timing oscillators and related methods|
|US8058769||16 Dec 2009||15 Nov 2011||Sand9, Inc.||Mechanical resonating structures including a temperature compensation structure|
|US8064124||28 May 2008||22 Nov 2011||Qualcomm Mems Technologies, Inc.||Silicon-rich silicon nitrides as etch stops in MEMS manufacture|
|US8068268||3 Jul 2007||29 Nov 2011||Qualcomm Mems Technologies, Inc.||MEMS devices having improved uniformity and methods for making them|
|US8111108||29 Jul 2008||7 Feb 2012||Sand9, Inc.||Micromechanical resonating devices and related methods|
|US8149497||24 Feb 2010||3 Apr 2012||Qualcomm Mems Technologies, Inc.||Support structure for MEMS device and methods therefor|
|US8179201 *||28 Sep 2010||15 May 2012||Nxp B.V.||Resonator|
|US8218229||24 Feb 2010||10 Jul 2012||Qualcomm Mems Technologies, Inc.||Support structure for MEMS device and methods therefor|
|US8226836||12 Aug 2008||24 Jul 2012||Qualcomm Mems Technologies, Inc.||Mirror and mirror layer for optical modulator and method|
|US8258893||30 Jun 2011||4 Sep 2012||Silicon Laboratories Inc.||Out-of-plane MEMS resonator with static out-of-plane deflection|
|US8284475||1 Apr 2010||9 Oct 2012||Qualcomm Mems Technologies, Inc.||Methods of fabricating MEMS with spacers between plates and devices formed by same|
|US8298847||23 Apr 2010||30 Oct 2012||Qualcomm Mems Technologies, Inc.||MEMS devices having support structures with substantially vertical sidewalls and methods for fabricating the same|
|US8362675||7 Nov 2011||29 Jan 2013||Sand 9, Inc.||Mechanical resonating structures including a temperature compensation structure|
|US8410868||17 May 2010||2 Apr 2013||Sand 9, Inc.||Methods and apparatus for temperature control of devices and mechanical resonating structures|
|US8464418||15 Dec 2009||18 Jun 2013||Silicon Laboratories Inc.||Method for temperature compensation in MEMS resonators with isolated regions of distinct material|
|US8471641||30 Jun 2011||25 Jun 2013||Silicon Laboratories Inc.||Switchable electrode for power handling|
|US8476809||8 May 2012||2 Jul 2013||Sand 9, Inc.||Microelectromechanical systems (MEMS) resonators and related apparatus and methods|
|US8587183||20 Nov 2012||19 Nov 2013||Sand 9, Inc.||Microelectromechanical systems (MEMS) resonators and related apparatus and methods|
|US8629599||7 Nov 2011||14 Jan 2014||Sand 9, Inc.||Mechanical resonating structures including a temperature compensation structure|
|US8629739||30 Aug 2012||14 Jan 2014||Silicon Laboratories Inc.||Out-of plane MEMS resonator with static out-of-plane deflection|
|US8638179||20 Dec 2011||28 Jan 2014||Sand 9, Inc.||Micromechanical resonating devices and related methods|
|US8659816||25 Apr 2011||25 Feb 2014||Qualcomm Mems Technologies, Inc.||Mechanical layer and methods of making the same|
|US8669831||19 Nov 2010||11 Mar 2014||Silicon Laboratories Inc.||Method for temperature compensation in MEMS resonators with isolated regions of distinct material|
|US8686614||16 Dec 2009||1 Apr 2014||Sand 9, Inc.||Multi-port mechanical resonating devices and related methods|
|US8689426||19 Jul 2011||8 Apr 2014||Sand 9, Inc.||Method of manufacturing a resonating structure|
|US8698376||20 Nov 2012||15 Apr 2014||Sand 9, Inc.||Microelectromechanical systems (MEMS) resonators and related apparatus and methods|
|US8700199 *||21 Mar 2011||15 Apr 2014||International Business Machines Corporation||Passive resonator, a system incorporating the passive resonator for real-time intra-process monitoring and control and an associated method|
|US8830557||10 Sep 2012||9 Sep 2014||Qualcomm Mems Technologies, Inc.||Methods of fabricating MEMS with spacers between plates and devices formed by same|
|US8937425||7 Dec 2011||20 Jan 2015||Sand 9, Inc.||Mechanical resonating structures including a temperature compensation structure|
|US9013245||18 Jun 2012||21 Apr 2015||Sand 9, Inc.||Oscillators having arbitrary frequencies and related systems and methods|
|US9030080||20 Nov 2012||12 May 2015||Sand 9, Inc.||Microelectromechanical systems (MEMS) resonators and related apparatus and methods|
|US9048811||1 May 2013||2 Jun 2015||Sand 9, Inc.||Integration of piezoelectric materials with substrates|
|US9075077||16 Sep 2011||7 Jul 2015||Analog Devices, Inc.||Resonant sensing using extensional modes of a plate|
|US9238576||8 Jan 2014||19 Jan 2016||Industrial Technology Research Institute||Composite micro-electro-mechanical-system apparatus and manufacturing method thereof|
|US9383208||12 Oct 2012||5 Jul 2016||Analog Devices, Inc.||Electromechanical magnetometer and applications thereof|
|US9401693||27 Feb 2013||26 Jul 2016||Analog Devices, Inc.||Methods and apparatus for temperature control of devices and mechanical resonating structures|
|US9422157||23 May 2013||23 Aug 2016||Semiconductor Manufacturing International (Shanghai) Corporation||Method for temperature compensation in MEMS resonators with isolated regions of distinct material|
|US9602074||9 Dec 2014||21 Mar 2017||Analog Devices, Inc.||Mechanical resonating structures including a temperature compensation structure|
|US9651376||28 Jan 2014||16 May 2017||Analog Devices, Inc.||Microelectromechanical gyroscopes and related apparatus and methods|
|US9762202||11 Feb 2014||12 Sep 2017||Analog Devices, Inc.||Method of manufacturing a mechanical resonating structure|
|US20060066932 *||25 Mar 2005||30 Mar 2006||Clarence Chui||Method of selective etching using etch stop layer|
|US20060077519 *||22 Jul 2005||13 Apr 2006||Floyd Philip D||System and method for providing thermal compensation for an interferometric modulator display|
|US20060256420 *||31 Mar 2006||16 Nov 2006||Miles Mark W||Film stack for manufacturing micro-electromechanical systems (MEMS) devices|
|US20070019922 *||21 Jul 2006||25 Jan 2007||Teruo Sasagawa||Support structure for MEMS device and methods therefor|
|US20070042524 *||18 Aug 2006||22 Feb 2007||Lior Kogut||MEMS devices having support structures with substantially vertical sidewalls and methods for fabricating the same|
|US20070047900 *||21 Jul 2006||1 Mar 2007||Sampsell Jeffrey B||MEMS devices having support structures and methods of fabricating the same|
|US20070096300 *||28 Oct 2005||3 May 2007||Hsin-Fu Wang||Diffusion barrier layer for MEMS devices|
|US20070249079 *||19 Apr 2006||25 Oct 2007||Teruo Sasagawa||Non-planar surface structures and process for microelectromechanical systems|
|US20070277620 *||2 Jun 2006||6 Dec 2007||Renata Melamud||Composite mechanical transducers and approaches therefor|
|US20070279753 *||1 Jun 2006||6 Dec 2007||Ming-Hau Tung||Patterning of mechanical layer in MEMS to reduce stresses at supports|
|US20080041817 *||26 Oct 2007||21 Feb 2008||Qualcomm Mems Technologies, Inc.||Structure of a micro electro mechanical system and the manufacturing method thereof|
|US20080055699 *||26 Oct 2007||6 Mar 2008||Qualcomm Mems Technologies, Inc||Structure of a micro electro mechanical system and the manufacturing method thereof|
|US20080094686 *||19 Oct 2006||24 Apr 2008||U Ren Gregory David||Sacrificial spacer process and resultant structure for MEMS support structure|
|US20080144163 *||7 Feb 2008||19 Jun 2008||Idc, Llc||Device and method for modifying actuation voltage thresholds of a deformable membrane in an interferometric modulator|
|US20080204173 *||21 Jan 2008||28 Aug 2008||Renata Melamud||Composite mechanical transducers and approaches therefor|
|US20080226929 *||28 May 2008||18 Sep 2008||Qualcomm Mems Technologies, Inc.||Silicon-rich silicon nitrides as etch stop in mems manufacture|
|US20080279498 *||27 Sep 2007||13 Nov 2008||Qualcomm Incorporated||Mems structures, methods of fabricating mems components on separate substrates and assembly of same|
|US20080310008 *||14 Jun 2007||18 Dec 2008||Qualcomm Incorporated||Method of patterning mechanical layer for mems structures|
|US20080314866 *||12 Aug 2008||25 Dec 2008||Idc, Llc.||Mirror and mirror layer for optical modulator and method|
|US20090009444 *||3 Jul 2007||8 Jan 2009||Qualcomm Incorporated||Mems devices having improved uniformity and methods for making them|
|US20090267699 *||29 Apr 2008||29 Oct 2009||Sand9||Timing oscillators and related methods|
|US20090267700 *||29 Apr 2008||29 Oct 2009||Sand9||Timing oscillators and related methods|
|US20100019336 *||27 Jul 2009||28 Jan 2010||Qualcomm Mems Technologies, Inc.||Mems devices having overlying support structures and methods of fabricating the same|
|US20100026136 *||29 Jul 2008||4 Feb 2010||Sand9, Inc||Micromechanical resonating devices and related methods|
|US20100093125 *||15 Dec 2009||15 Apr 2010||Quevy Emmanuel P||Method for temperature compensation in mems resonators with isolated regions of distinct material|
|US20100147790 *||24 Feb 2010||17 Jun 2010||Qualcomm Mems Technologies, Inc.||Support structure for mems device and methods therefor|
|US20100149627 *||24 Feb 2010||17 Jun 2010||Qualcomm Mems Technologies, Inc.||Support structure for mems device and methods therefor|
|US20100181868 *||16 Dec 2009||22 Jul 2010||Sand9, Inc.||Multi-port mechanical resonating devices and related methods|
|US20100182102 *||16 Dec 2009||22 Jul 2010||Sand9, Inc.||Mechanical resonating structures including a temperature compensation structure|
|US20100182675 *||1 Apr 2010||22 Jul 2010||Qualcomm Mems Technologies, Inc.||Methods of fabricating mems with spacers between plates and devices formed by same|
|US20100202039 *||23 Apr 2010||12 Aug 2010||Qualcomm Mems Technologies, Inc.||Mems devices having support structures with substantially vertical sidewalls and methods for fabricating the same|
|US20100315179 *||17 May 2010||16 Dec 2010||Sand9, Inc.||Methods and apparatus for temperature control of devices and mechanical resonating structures|
|US20110080224 *||28 Sep 2010||7 Apr 2011||Nxp B.V.||Resonator|
|US20110084781 *||19 Nov 2010||14 Apr 2011||Silicon Labs Sc, Inc.||Method For Temperature Compensation In MEMS Resonators With Isolated Regions Of Distinct Material|
|US20110175492 *||19 Jan 2011||21 Jul 2011||Imec||Temperature Compensation Device and Method for MEMS Resonator|
|US20120245724 *||21 Mar 2011||27 Sep 2012||International Business Machines Corporation||Passive resonator, a system incorporating the passive resonator for real-time intra-process monitoring and control and an associated method|
|EP2348633A1||21 Jan 2011||27 Jul 2011||Imec||Temperature compensation device and method for MEMS resonator|
|EP2362199A1||18 Jun 2010||31 Aug 2011||Imec||Temperature measurement system comprising a resonant mems device|
|WO2007143520A2 *||1 Jun 2007||13 Dec 2007||The Board Of Trustees Of The Leland Stanford Junior University||Composite mechanical transducers and approaches therefor|
|WO2007143520A3 *||1 Jun 2007||26 Feb 2009||Univ Leland Stanford Junior||Composite mechanical transducers and approaches therefor|
|U.S. Classification||333/186, 333/197, 333/219|
|International Classification||H03H9/00, H03H9/02, H03H, H01P7/10, H03H9/54, H03H9/50, H03H9/24|
|Cooperative Classification||B81B3/0072, H03H9/2457, H03H9/02448, H03H2009/02511, H03H2009/02496, H03H9/02259, H03H9/2463, H03H9/02338, B81B2203/0118, H03H9/02417, B81B2201/0271|
|European Classification||B81B3/00S2S, H03H9/02M8B, H03H9/02M6F, H03H9/02M4, H03H9/24M8D, H03H9/02M2, H03H9/24M8F|
|30 Jun 2003||AS||Assignment|
Owner name: ROBERT BOSCH GMBH, GERMANY
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LUTZ, MARKUS;PARTRIDGE, AARON;REEL/FRAME:014222/0649
Effective date: 20030624
|6 Jul 2009||FPAY||Fee payment|
Year of fee payment: 4
|12 Mar 2013||FPAY||Fee payment|
Year of fee payment: 8
|11 Jul 2017||FPAY||Fee payment|
Year of fee payment: 12